1. Field of the Invention
This invention relates generally to computer controlled vehicle subsystems, and especially to auxiliary fuel tank control equipments which are adaptable to many classes of vehicles, and which include on-board diagnostic (OBD) capabilities. The system is designed to work with both new and used main fuel systems, and can provide OBD capability to either system.
Computer controlled vehicle subsystems have long been used on vehicles to control various vehicle subsystems such as engine, ignition, transmission, brake, and suspension systems. Due to the complexity and inter-relationship between some of these vehicle systems, buses, or other on-board computer communication systems, have been developed to enable data and control signals to be passed between particular vehicle computers. Because of the heavy reliance on such on-board computers, combined with the variety of system types employed by the various automobile manufacturers, vehicles sold in the United States now are required to provide a standardized diagnostic interface to facilitate compatibility with standardized diagnostic scan tools. In California, this restriction is referred to as the CARB OBD (California Air Resources Board On Board Diagnostics 11, or EPA OBDII (Environmental Protection Agency On Board Diagnostics II) requirements, and have been applied to new vehicles beginning with the 1996 model year and to all vehicles in the 1998 model year. This applies to vehicles under 14000 lbs. GVWR in California and under 8600 lbs. GVWR outside California.
2. Background Art
Fuel transfer systems are, in general, well known. Sasaki, et al, in U.S. Pat. No. 4,834,132 for a Fuel Transfer Apparatus, describes a fuel transfer system for transferring fuel from a first sump to a second sump formed in a fuel tank used in an automotive vehicle.
U.S. Pat. No. 4,951,699 to Lipman for a Fuel Transfer System with Aspirator, shows a device and system to transport fuel from the interior portion of a fuel tank to another tank by automatic siphon action. An aspirator that evacuates air and fuel vapor from the siphon by the flow effect of the return fuel through a venturi or reduced diameter portion of the return fuel line initiates the siphon.
It is generally well known to provide special apparatus for verifying the operation of a data processing system. Some systems include separate maintenance or auxiliary processing units for testing different subsystems during normal operation or during a test mode of operation. It is also well known to include an internal testing capability integrated within the processing units of a system for establishing a certain level of operability. An example is seen in U.S. Pat. No. 5,548,713, in which Petry et al describe an on-board diagnostic testing apparatus which can test a processing unit in a system, and which also is usable in a factory test environment.
Communications of diagnostic test results are also known. Berra et al, in U.S. Pat. No. 5,555,498 describes a circuit and method for interfacing vehicle controller and diagnostic test instruments. An adapter is provided which permits the use of present diagnostic tools with newer ISO9141 equipped engine and transmission controllers. The adapter facilitates bidirectional communication while conditioning the signals entering and exiting the adapter.
Machida et al, in U.S. Pat. No. 5,592,923, describe diagnosis apparatus for treating fuel vapor of an engine, in which the fuel vapor in a fuel tank is once adsorbed and trapped in a canister and is then supplied to the intake system of an engine, wherein various valves are so controlled that a predetermined pressure condition is established in a passage for supplying the fuel vapor, and said various valves are diagnosed to determine whether they are defective or not, based upon pressure measurements against a norm.
Fundamental difficulties in obtaining low cost, accurate, and repeatable fuel level measurement systems have been recognized. A float-level sensor, including an immersed resistive sender element, has become a common standard, but it is known to be subject to effects of contact corrosion associated with various additives in the fuel. Gonze, in U.S. Pat. No. 4,782,699, combats alcohol caused corrosion by applying a 1-millisecond current pulse to the detector once a minute. In U.S. Pat. No. 5,172,007, Lumetta describes the problems associated with these common senders when immersed in so-called xe2x80x9cflexible fuelsxe2x80x9d being developed for reduced hydrocarbon emissions. His specific solutions have been shown to be effective with M-85 (85% methyl alcohol and 15% gasoline) fuel when switched between 100 Hz and 15 kHz, but nothing is taught regarding more common gasoline fuels incorporating modern additives.
This system is designed to provide one or more auxiliary fuel sources as original equipment with new vehicles, or as an aftermarket addition to an older vehicle. The auxiliary system controls and monitors each fuel system and their associated fuel display. Fuel levels in each tank are balanced, diagnostic data is obtained from the performance of each system, and corrective actions including operator warnings are given. Although the original equipments may have their own computer controlled diagnostic capabilities, the auxiliary computer runs standard tests on all fuel systems. Each system""s fuel tank senders are pulse-preconditioned prior to reading in a similar manner, with a technique unique to this invention.
The auxiliary fuel system of this invention comprises an auxiliary fuel tank, having an auxiliary fuel pump, a sending unit, check valves, inlet and outlet fuel lines, a wiring harness, a computer module, an auxiliary emissions canister assembly, vehicle installation means, and a liquid crystal display (LCD) device. In a typical installation in a pickup truck, the main original equipment manufacturer (OEM) fuel tank is sized around 30 gallons. The Auxiliary Fuel Tank is typically a 30-gallon tank that is mounted at the head of the pickup box. The computer module is mounted under the dash near the steering column. The Auxiliary emissions canister assembly is mounted near the OEM emissions canister assembly. The pump/sender is mounted in the Auxiliary tank. The wire harness routes from the computer module to the Auxiliary pump/sender, to the Auxiliary pressure sensor, to the OEM pump/sender, to the OEM pressure sensor, to the OEM fresh air vent solenoid valve, to the Auxiliary tank solenoid valve, to the OEM tank solenoid valve, to 12-volt power, and to chassis and OEM computer ground. The system functions as a computer controlled balance line. The computer monitors the entire system approximately once every four seconds. During each loop the fuel levels of the OEM and the Auxiliary tanks are determined. The Liquid Crystal Display (LCD) will indicate the gallons in the OEM tank, the gallons in the Auxiliary tank, the total gallons in the system, and the status of the system. The computer will also adjust the OEM fuel gauge accordingly.
It will be noted that the capacity ratio of a typical single Auxiliary tank to a single OEM tank is 1:1. During the transfer process, when the OEM tank is two gallons less than the gallons in the Auxiliary tank, the Auxiliary fuel pump will turn on and transfer fuel to the OEM tank. The transfer ends when the OEM tank is equal to the gallons in the Auxiliary tank. When the Auxiliary pump is on, the LCD will display xe2x80x9cPMP ONxe2x80x9d.
The Auxiliary fuel system of this invention also includes an On-Board-Diagnostics (OBD) capability. This system detects multiple problems that occur upon installation and during normal use. When a problem occurs for a set period of time, say at least 30 seconds, the computer will detect the problem and display the Diagnostic Trouble Code (DTC) associated with that problem on the LCD. A red light-emitting diode, (LED) will also be blinked a specific number of times for operator warning. After the problem has been displayed, and if it is the first problem that has occurred during that driving cycle, the computer will store that problem in its memory. The computer will then send the fuel gauge to empty and set the Auxiliary and Main tank gallon""s readings to zero. This will let the driver know that there is a problem. This system addresses five (5) different basic problems. These problems, with their visual display indications, are as follows:
1) Main Sender Grounded. (MSG), 1 LED Display Blink.
The Main Sender Ground DTC is set when the resistance from the main sender drops below a predetermined set point, approaching ground. A malfunctioning sending unit or a wire rubbing against ground could cause this condition.
2) Main Sender Open (MSO) 2 LED Display Blinks.
The Main Sender Open DTC is set when the main sender resistance raises above a predetermined set point, i.e. toward an open circuit condition. This condition could be caused by wire corrosion or by a broken wire.
3) Auxiliary Sender Ground (ASG), 3 LED Display Blinks.
This DTC is set in a manner similar to the MSG, but can have different predetermined set points.
4) Auxiliary Sender Open (ASO), 4 LED Display Blinks.
This DTC is set in a manner similar to the MSO, but can also have different predetermined set points.
5). No flow problem (NO FLW), 5 LED Display Blinks.
The No Flow Problem is set if the auxiliary pump is turned ON, and if the fuel level in the Auxiliary tank has not dropped by a predetermined amount. This condition may indicate a crimped line, a malfunctioning pump, or a broken wiring connection.
This Auxiliary fuel system is compatible with OBDII enhanced evaporative emissions testing, which is required on all new 1998 fuel-injected gas vehicles under 14,000 GVW in California and under 8600 lbs. outside California. The Auxiliary fuel system is transparent to the OEM computer, in that the OEM computer is not aware that an Auxiliary fuel system has been added.
It is a principal object of this invention to provide a computer controlled auxiliary fuel system, which is compliant with the CARB OBD (California Air Resources Board, On Board Diagnostics II) and with the EPA OBDII, (Environmental Protection Agency On Board Diagnostics II) requirements.
It is an additional object of this invention to provide a computer controlled auxiliary fuel system, which is compatible with a vehicle""s existing main fuel system.
It is another object of this invention to provide a computer controlled auxiliary fuel system, which is transparent to the main fuel system""s computer.
It is a further object of this invention to provide a computer controlled auxiliary fuel system, which includes self-diagnostic capabilities.
It is another object of this invention to provide a computer controlled auxiliary fuel system that is useable in both original, and after-market equipments.
It is yet another object of this invention to provide a means of measuring a standard fuel level sender with repeated accuracy by use of a computer controlled pulsing system.
Further objects of this invention include the provision of a reliable computer controlled auxiliary fuel system which may be inexpensively manufactured, is structurally rigid and safe, and can be easily installed in both current and older model vehicles.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description, when making reference to the detailed description and to the accompanying sheets of drawings.